North Eastern Hill University

About: North Eastern Hill University is a education organization based out in Shillong, Meghalaya, India. It is known for research contribution in the topics: Population & Catalysis. The organization has 2318 authors who have published 4476 publications receiving 48894 citations.

Biomass and production of fine and coarse roots during regrowth of a disturbed subtropical humid forest in north-east india

Abstract: Seasonal variation and depthwise distribution of dry matter in roots of different diameter classes and their annual production were studied using sequential core sampling. The investigations were carried out in three stands of a subtropical humid forest of north-east India representing different stages of regrowth after tree cutting. The mean annual standing crop of fine (<2 mm in diameter) and coarse (2–15 mm diameter) roots increased gradually from 5.4 Mg ha-1 and 0.7 Mg ha-1 in 7-yr old regrowth to 9.4 Mg ha-1 and 2.8 Mg ha-1 in 16-yr old regrowth, respectively. The contribution of fine roots to the total root mass declined from 88% in 7-yr old regrowth to 77% in both 13 and 16-yr old regrowths, while that of coarse roots increased from 12 to 23%. A major portion of fine roots (59–62%) was present in 0–10 cm soil layer, but the coarse roots were concentrated in 10–20 cm soil depth (38–48%). In all the three stands, biomass of both fine and coarse roots followed a unimodal growth curve by showing a gradual increase from spring/pre-rainy season to autumn/post-rainy season. Biomass to necromass ratio increased from 2.5 in the 7-yr old to 3.2 in the 16-yr old stand. The annual fine root production increased from 5.9 Mg ha-1 to 7.7 Mg ha-1 and total root production from 7.6 Mg ha-1 to 14.7 Mg ha-1 from 7-yr to 16-yr old regrowth.

Synthesis and evaluation of new salicylaldehyde-2-picolinylhydrazone Schiff base compounds of Ru(II), Rh(III) and Ir(III) as in vitro antitumor, antibacterial and fluorescence imaging agents

Abstract: Reaction of salicylaldehyde-2-picolinylhydrazone (HL) Schiff base ligand with precursor compounds [{(p-cymene)RuCl2}2] 1, [{(C6H6)RuCl2}2] 2, [{Cp*RhCl2}2] 3 and [{Cp*IrCl2}2] 4 yielded the corresponding neutral mononuclear compounds 5-8, respectively. The in vitro antitumor evaluation of the compounds 1-8 against Dalton's ascites lymphoma (DL) cells by fluorescence-based apoptosis study and by their half-maximal inhibitory concentration (IC50) values revealed the high antitumor activity of compounds 3, 4, 5 and 6. Compounds 1-8 render comparatively lower apoptotic effect than that of cisplatin on model non-tumor cells, i.e., peripheral blood mononuclear cells (PBMC). The antibacterial evaluation of compounds 5-8 by agar well-diffusion method revealed that compound 6 is significantly effective against all the eight bacterial species considered with zone of inhibition up to 35 mm. Fluorescence imaging study of compounds 5-8 with plasmid circular DNA (pcDNA) and HeLa RNA demonstrated their fluorescence imaging property upon binding with nucleic acids. The docking study with some key enzymes associated with the propagation of cancer such as ribonucleotide reductase, thymidylate synthase, thymidylate phosphorylase and topoisomerase II revealed strong interactions between proteins and compounds 5-8. Conformational analysis by density functional theory (DFT) study has corroborated our experimental observation of the N, N binding mode of ligand. Compounds 5-8 exhibited a HOMO (highest occupied molecular orbital)-LUMO (lowest unoccupied molecular orbital) energy gap 2.99-3.04 eV. Half-sandwich ruthenium, rhodium and iridium compounds were obtained by treatment of metal precursors with salicylaldehyde-2-picolinylhydrazone (HL) by in situ metal-mediated deprotonation of the ligand. Compounds under investigation have shown potential antitumor, antibacterial and fluorescence imaging properties. Arene ruthenium compounds exhibited higher activity compared to that of Cp*Rh/Cp*Ir in inhibiting the cancer cells growth and pathogenic bacteria. At a concentration 100 µg/mL, the apoptosis activity of arene ruthenium compounds, 5 and 6 (~30 %) is double to that of Cp*Rh/Cp*Ir compounds, 7 and 8 (~12 %). Among the four new compounds 5-8, the benzene ruthenium compound, i.e., compound 6 is significantly effective against the pathogenic bacteria under investigation.

Biological Activity of Endophytic Fungi of Rauwolfia serpentina Benth: An Ethnomedicinal Plant Used in Folk Medicines in Northeast India

Abstract: Rauwolfia serpentina Benth is an ethnomedicinal plant used as anti-hypertensive remedy by the ethnic tribes of northeast India. The plant was screened for the endophytic fungi and their associated biological activities to assess if these fungi have any significant hypocholesterolemic, anti-oxidant and antimicrobial activities. The endophytes were characterized as Colletotrichum gloeosporioides, Penicillium sp. and Aspergillus awamori, from a total 15 isolates, using biochemical and molecular approaches. The colonization rate of endophytes in the leaf and the stem was found to be 12.04 and 4.02 % respectively. C. gloeosporioides was found to be the dominant fungus with an average colonization frequency of 6.8 % followed by Penicillium sp. (3.8 %) and A. awamori (2.1 %). Being the most potential isolate, Penicillium sp. showed the promising hypocholesterolemic activity. The antimicrobial potential against four pathogenic bacteria, viz., Streptococcus pyogenes, Escherichia coli, Enterococcus faecalis, Salmonella enterica ser paratyphi and three fungal pathogens, viz, Candida albicans, Emericella nidulans var nidulans, Fusarium oxysporum showed promising antagonistic ability. A. awamori showed the highest antioxidant potential and also had the maximum phenolic content among the characterized endophytes. This investigation revealed that the endophytic fungal extracts can be a potential source of alternative natural hypocholesterolemic, antimicrobials and antioxidant agents mimicking the activity of the host plant and purification of active metabolites may provide lead molecule of pharmaceutical importance.